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b7cdc182 | 1 | /* SPDX-License-Identifier: GPL-2.0-only |
9f36eaed | 2 | * |
f3bc08c5 MD |
3 | * ring_buffer_mmap.c |
4 | * | |
5 | * Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp | |
6 | * Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com> | |
886d51a3 | 7 | * Copyright (C) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
f3bc08c5 | 8 | * |
b7cdc182 | 9 | * Re-using code from kernel/relay.c, hence the GPL-2.0-only license for this |
886d51a3 | 10 | * file. |
f3bc08c5 MD |
11 | */ |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/mm.h> | |
15 | ||
24591303 MD |
16 | #include <ringbuffer/backend.h> |
17 | #include <ringbuffer/frontend.h> | |
18 | #include <ringbuffer/vfs.h> | |
f3bc08c5 MD |
19 | |
20 | /* | |
21 | * fault() vm_op implementation for ring buffer file mapping. | |
22 | */ | |
05355f0b MJ |
23 | #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,1,0) || \ |
24 | LTTNG_RHEL_KERNEL_RANGE(4,18,0,193,0,0, 4,19,0,0,0,0)) | |
2ca0c84f MJ |
25 | static vm_fault_t lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) |
26 | #else | |
52a391bd | 27 | static int lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf) |
2ca0c84f | 28 | #endif |
f3bc08c5 | 29 | { |
e20c0fec | 30 | struct lttng_kernel_ring_buffer *buf = vma->vm_private_data; |
860c213b | 31 | struct lttng_kernel_ring_buffer_channel *chan = buf->backend.chan; |
e20c0fec | 32 | const struct lttng_kernel_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 | 33 | pgoff_t pgoff = vmf->pgoff; |
0112cb7b | 34 | unsigned long *pfnp; |
f3bc08c5 MD |
35 | void **virt; |
36 | unsigned long offset, sb_bindex; | |
37 | ||
f3bc08c5 MD |
38 | /* |
39 | * Verify that faults are only done on the range of pages owned by the | |
40 | * reader. | |
41 | */ | |
42 | offset = pgoff << PAGE_SHIFT; | |
43 | sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id); | |
44 | if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset | |
45 | && offset < buf->backend.array[sb_bindex]->mmap_offset + | |
46 | buf->backend.chan->backend.subbuf_size)) | |
47 | return VM_FAULT_SIGBUS; | |
48 | /* | |
0112cb7b MD |
49 | * ring_buffer_read_get_pfn() gets the page frame number for the |
50 | * current reader's pages. | |
f3bc08c5 | 51 | */ |
0112cb7b MD |
52 | pfnp = lib_ring_buffer_read_get_pfn(&buf->backend, offset, &virt); |
53 | if (!*pfnp) | |
f3bc08c5 | 54 | return VM_FAULT_SIGBUS; |
0112cb7b MD |
55 | get_page(pfn_to_page(*pfnp)); |
56 | vmf->page = pfn_to_page(*pfnp); | |
f3bc08c5 MD |
57 | |
58 | return 0; | |
59 | } | |
60 | ||
05355f0b MJ |
61 | #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,1,0) || \ |
62 | LTTNG_RHEL_KERNEL_RANGE(4,18,0,193,0,0, 4,19,0,0,0,0)) | |
2ca0c84f MJ |
63 | static vm_fault_t lib_ring_buffer_fault(struct vm_fault *vmf) |
64 | { | |
65 | struct vm_area_struct *vma = vmf->vma; | |
66 | return lib_ring_buffer_fault_compat(vma, vmf); | |
67 | } | |
5f4c791e | 68 | #elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,11,0)) |
52a391bd FD |
69 | static int lib_ring_buffer_fault(struct vm_fault *vmf) |
70 | { | |
71 | struct vm_area_struct *vma = vmf->vma; | |
72 | return lib_ring_buffer_fault_compat(vma, vmf); | |
73 | } | |
5f4c791e | 74 | #else /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,11,0)) */ |
52a391bd FD |
75 | static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
76 | { | |
77 | return lib_ring_buffer_fault_compat(vma, vmf); | |
78 | } | |
5f4c791e | 79 | #endif /* #else #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,11,0)) */ |
52a391bd | 80 | |
f3bc08c5 MD |
81 | /* |
82 | * vm_ops for ring buffer file mappings. | |
83 | */ | |
84 | static const struct vm_operations_struct lib_ring_buffer_mmap_ops = { | |
85 | .fault = lib_ring_buffer_fault, | |
86 | }; | |
87 | ||
88 | /** | |
89 | * lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space | |
90 | * @buf: ring buffer to map | |
91 | * @vma: vm_area_struct describing memory to be mapped | |
92 | * | |
93 | * Returns 0 if ok, negative on error | |
94 | * | |
95 | * Caller should already have grabbed mmap_sem. | |
96 | */ | |
e20c0fec | 97 | static int lib_ring_buffer_mmap_buf(struct lttng_kernel_ring_buffer *buf, |
f3bc08c5 MD |
98 | struct vm_area_struct *vma) |
99 | { | |
100 | unsigned long length = vma->vm_end - vma->vm_start; | |
860c213b | 101 | struct lttng_kernel_ring_buffer_channel *chan = buf->backend.chan; |
e20c0fec | 102 | const struct lttng_kernel_ring_buffer_config *config = &chan->backend.config; |
f3bc08c5 MD |
103 | unsigned long mmap_buf_len; |
104 | ||
105 | if (config->output != RING_BUFFER_MMAP) | |
106 | return -EINVAL; | |
107 | ||
f3bc08c5 MD |
108 | mmap_buf_len = chan->backend.buf_size; |
109 | if (chan->backend.extra_reader_sb) | |
110 | mmap_buf_len += chan->backend.subbuf_size; | |
111 | ||
112 | if (length != mmap_buf_len) | |
113 | return -EINVAL; | |
114 | ||
115 | vma->vm_ops = &lib_ring_buffer_mmap_ops; | |
116 | vma->vm_flags |= VM_DONTEXPAND; | |
117 | vma->vm_private_data = buf; | |
118 | ||
119 | return 0; | |
120 | } | |
121 | ||
d83004aa | 122 | int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma, |
e20c0fec | 123 | struct lttng_kernel_ring_buffer *buf) |
d83004aa JD |
124 | { |
125 | return lib_ring_buffer_mmap_buf(buf, vma); | |
126 | } | |
127 | EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap); | |
128 | ||
f3bc08c5 | 129 | /** |
d83004aa | 130 | * vfs_lib_ring_buffer_mmap - mmap file op |
f3bc08c5 MD |
131 | * @filp: the file |
132 | * @vma: the vma describing what to map | |
133 | * | |
134 | * Calls upon lib_ring_buffer_mmap_buf() to map the file into user space. | |
135 | */ | |
d83004aa | 136 | int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma) |
f3bc08c5 | 137 | { |
e20c0fec | 138 | struct lttng_kernel_ring_buffer *buf = filp->private_data; |
d83004aa | 139 | return lib_ring_buffer_mmap(filp, vma, buf); |
f3bc08c5 | 140 | } |
d83004aa | 141 | EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap); |